Railway-traffic-controlling apparatus



H. A. WALLACE RAILWAY TRAFFIC CONTROLLING APPARATUS Apfil 24, 1928.

Filed May 25. 1923 e Sheets-Sheet 1 INVENT O R MQMM 13$ 6 Sheets-Sheet INYENTOR H. A. WALLAC'E RAILWI \Y TRAFFIC CONTROLLING APPARATUS Flled May 25, 1923 mdi April 24, 1928.

A ril 24, 1928. 1,667,577

' H. WALLACE RAILWAY TRAFFIC CONTROLLING APPARATUS File M y 25, 1923 -s sheets-sheet 3 FIG-.3.

. 'lNVE/VTOR a. W

April 24, 1928.

I 1 ,667,577 H. A. WALLACE RAILWAY TRAFFIC CONTROLLING APPARATUS Filed May 25 1923 e Sheets-Sheet 4 FIE-1.4.

, IAIIVENQTOR April 24, 1928.

FIE-1-5} 1,667,577 H. A. WALLACE RAILWAY TRAFFIC CONTROLLING APPARATUS Filed May 25, 1923 6 Sheets-Sheet 5 lA/VE/VTOR.

A ril 24, 1928.

H. A. WALLACE RAILWAY TRAFFIC CONTROLLING APPARATUS 6 t e m 0 5w m w o w @wwww S @w E\ R, e 3 w o 252 q m I lA/i/ENTOR P............ 24.19%. I 1,667,577 UNITED. STATES PATENT," OFFICE.

nnnnna'r A. warmer, or nncnwoozo Bonouen, rENN-snvANrA, assmNon 'rom UNION SWITCH & SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A. 0032015.

TION OF PENNSYLVANIA,

nAILwaY-rmrm-coNrnoLmNe Arrnnh'rus.

Application filed Kay 25,

My invention relates to railway trafiic controlling apparatus, and particularly toapparatus of the type wherein governing apparatus carried on a train is controlled by energy supplied from the trackway.

I will describe several forms and arrangements of railway tratfie controlling apparatus embodying my inventionfand will then point out the novel features thereof in "claims. 1

In the accompanying drawing, Fig. 1 is a diagrammatic view showing one form of trackway apparatus embodying my inven- Fig. 2 is a View showing a modification of he arrangement shown in Fig. 1 and also embodying my invention. Fig. 3 is a view I showing another modification of the trackway apparatus shown in Fig. '1 and also embodying my invention. Fig. 4 is a View showing another modification of the arrangement shown in Fig. 1 and also embodying my invention. Fig. 5 isa view showing still another arrangement of trackway apparatus embodying my invention.

. characters 2 and 2 designatethe rails of a section whereby railway track over which trailic' normally. travels in the directioniindicated by the arrow. These rails-are divided by insulated joints 1 into a plurality of track sections -A-B, B-C, etc.

Each track section is provided with a source oftrack circuit current which, as here shown, is a secondary winding 4 on a track transformer designated by thev reference character T with ELH'QXPOUGllt corresponding to the location, this secondary bei-ng con nee-ted across the rails at the exit, end of the section. An impedance 5 is interposed between this secondary. and one rail of the the current output of the 1' transformer is limited toa safe value when 1923." Serial No. 841,887.

terminals are short-circuited by the wheels w and axles of a train occupying the corresponding section. Each track section is also provided with a track relay designated by. the reference character R with an exponent corresponding to the location and connected w across the rails .at the entrance end of the sect1on. Thus, it will be 'seen that each track section is provided with a track circuit which comprises a transformer sec: q ondary 4:, the rails 2 and 2 of-the section a in series and a track relay B.

Each section is also provl The means for controlling these signals form II no part of my present invention and so are omitted from the drawing. It is suflicient to say that each signal indicates stop when the corresponding section is occupied, caution' when the corresponding section is unoccu+10 pied, and the section-next in advance is occupied, and ro'ceed when the corresponding section an the section next in advance are both unoccupied.

Associated with each signal is a changer designated by the reference c aracter P with anexponent corresponding to the location, which pole changer is operated by the semaphore-and assumes one position I when the semaphore is at proceed or caution, go

and another position when the semaphore is at stop. Each signal also operates a circuit controller designated by the reference character D with an exponent corresponding to the location. This circuit controller is open 5 when the semaphore is at stop, closed to one circuit when the semaphore is at caution and closed to another circuit when th e semaphore is at proceed;

The polanty of h lative instantaneous track circuit is controlled current in each by the pole changer, P for the signal immediately in advance. Referring for example,

T, when the associated si nal S is at proceed or caution, the .le y

to transformer hand terminal of the primary 3 ofthe transformer T is connected through wire 6, pole changer P, wires 8 and 9 to the upper ded with a-signal des gnated by the reference character S with an exponent corresponding to the location this signal havinga. semaphore capable of o B as Q of the line wires 11 and thence to the generator 12, while at the same, time, theright hand terminal of the primary 3 is connected 1 by wire 7, pole changer P and wire 10 to the 5 other of the line wiresll. The section to the left-of the point A is then supplied with track circuit current of what I shall term normal relative instantaneous .polarity When the signal S is at stop, the pole changor P assumes the position shown in the drawing at P andthe wire 6 is now connected to wire 10 while wire 7 is now connected to wire 9, thus the relative instantaneous polarlty of the transformer is reversed and the 5 section to the left of A is now supplied with track circuit current of what I shall term .reversel relative instantaneous polarity.

Each section is provided wlthan impedance 13 connected across the rails adjacent go the entrance end of the section, a similar impedance 16 connected across the rails adjacent the exit end of the section, and two more similar impedances 14 and 15 connected across the rails at an intermediate point.

26 Each section is also provided with a dc.-

vice for alternately making and breaking a circuit, which device is designated by the reference character E with an exponent corresponding to the location, and which device so as shown in Fig. 1 is a slow acting relay having a magnet coil connected in series-with its own back contact.

, Each section is also provided with means for supplying a current, which I shall here- 85 inafter call a .local current. to the rails ofthe section in parallel. As here shown the immediate source of local current for each section is a line transformer designated by the reference character G with an exponent 40 corresponding to the'location. Each of these transformers comprises a primary winding 17 constantly supplied with current from the -.line-wires 11 and 11, and two. secondary windings 18 and 19. Referring particularly to transformer G, the secondary winding .19 has a circuit over which localcurrent flows from its left hand terminal through wire 20 to the-mid-point' of the impedance 13 of section BC, through both rails of section B-C in parallel, through the halves of the impedance 14,. and wire 21 back to theright hand terminal of't-he secondary 19 on transformer G The'otherseconda'ry 18 or transformer G'r has a circuit which passesv it from its left hand terminal through wire 36 to the mid-point of the impedance 15, through both rails of the section A--B in parallel, through the impedance 16, wires 34- and 33, back contact 31-32 of the slow act- 00 ing relay E 3, wire 30, energizing winding of the relay E, wire 29, contact 26-27 of circuit controller D wire 25, front contact 23-- of track relay R and wire 22 back to the right hand terminal of the winding 18 on 66 transformer-G This circuit is closed only when relay B is energized, relay E is deenergized, and signal S is at the caution position under which conditions relay E alternately opens and closes its back contact, as explained in detail hereinafter, and local current is then intermittently supplied to the rails of section AB between impedances 15 and 16. This circuit is provided with a branch which passes from wire 34, through wire 35, contact 2 6-28 011 circuit controller D back to wire 25, thus omitting relay E.

This branch is closed only when signal S is in the proceedposition. The local current then supplied to the track rails of section AB is uninterrupted.

One form of train carried apparatus. designed to cooperate with the trackway clrcuits and apparatus shown in Fig. 1 1s shown in Fig. 6. This equipment comprises two inverted U-shaped magnetizable cores 22' mounted in front of the first axleZ on the locomotive and arranged transversely above the two track rails 2 and 2", respec-v l .tively, each of these cores being provided with a winding designated F Located'atil some other point on the. train, suchas in the rear of the first axle, isanother pair of magnetlzable' cores 22 located above the track rails2 and 2, respectively, and disposed transversely with'rcspect thereto. each of these cores carrying a winding designated F The windings F are so connected that the-voltages induced therein due to current flowing in opposite directions in the two rails at any given instant are addi tive, and so it will be seen that track circuit current in the 'rails will induce current in the circuit including the windings F These two windings I will hereinafter refer to collectively as the track coil. The

two windings F? are so connected that the voltagesinduced therein by currents flowing in the same direction in the two "ra ls at a given instant are additive and so it w ll be seen that local, current in the track rails will indnce current in the circuit including.

the winding F These two windings Iwill hereinafter refer to collectively as the-local coil. The terminals a and I) of the track coil F are connected through suitable amplifying means K, to the winding 37 on a with local current and track circuit current,

I the relative polarity of either of which currents is reversed, the relay N is energized so I that the fingers 39, 40 and 41 are swung to the direction of nergization of relay .N. depends upon the relative polarity of the track circuit and local currents rather than upon the absolute polarity of either of these currents at any instant. Two magnets H and i M are also provided on each locomotive and are so. arranged in combination with'certain'g'overning apparatus not shown in the drawing that when the magnet H is energized and the magnet M is de-energized, the v governing apparatus permits the train to proceed at righ-speed such as miles per hour. When the magnet H is de-energized, and the magnet M is energized, the governing apparatus prevents the train from exceeding an. intermediate speed of 35 miles per hour. When magnets H and M are both de-energized the governing apparatus prevents the train from proceeding at speeds in excess of a low value, such as 10, miles per hour. The high speed magnet H is provided "with a circuit which passes from the left hand terminal of a source of energy such as a battery 0 through wires 47 and 48, normal contact 4146- on relay N, wire 49, winding of magnet H, and wires 5.0, 51 and 52, back to the right hand terminal of the battery 0. This circuit is closed only when the relay N is energized in the normal direct-ion. The magnet M is provided with a circuit which passes from the left hand terminal of the battery 0', through wires 47 and 48,- reverse contact 4145 of relay N,

wire 54, winding of the magnet M, and wires 53and52, back to the right hand terminal "of the battery O. 'This circuit is closed only when the relay N is energized in the reverse direction.

- The locomotive is also provided with a slow-acting relay J and an indicating device as alamp 200. The lamp 200 is provided with a circuit whichpasses from the left hand terminal of the battery 0, "through wires 47,- 55, 56 and 61, normal contact- 39 42 of relay N. wire 63. front contact 63 of relay J. wire 60, lamp 200, and jwires 64, 51 and 52 backto the right hand terminal of battery 0. This circuit is provided with a branch running from wire 56, through wire 62, reverse contact 39-43'on relay N and back to wire It follows that the zcircuitfor the'lamp is closed when the relay N. is energized in either 'the normal or reverse direction and the relay J is also energized. This relay J is provided with a circuit which passes from the left hand terminal ofbattery 0, through wires 47, 55 and 57, back contact 40-44 on relay N, wire 58, winding of relay J, and wires 59, 64, 51

and 52, back to the right hand terminal of tweenthe impedanees 15 and 16. The rails of the section 11-13 are supplied with track circuit current of normal relative polarity by transformer T and with local current between impedances 13 and 14 by transformer G". Since the signal S is at cantion, local current is supplied to section AB from 15 to 16 through slow-acting relay E As soon as this circuit is closed, however, relay E opens its back contact 3132, thus interrupting theflow of local current between the impedances 15 and 16. This also opens the circuit to the coil of the 'relay which becomes de-energized and after a definite time interval closes its back con tact, thus repeating the cycle and alternate- 1y closing and opening the circuit for the local current in section A- 3 between impedances 15 and 16.. Inasmuch as signal S is at proceed position, the section to the left of A is supplied with local current and with track current of normal relative polarity.

gzed. The governing mechanism controlled by magnets H and M require a definite time intervalto operate and this mechanism is so designed that the time intervals between successive de-energizations of relay N is less than the time required for the governing mechanism to act and hence this equipment does not have time to reduce the speed. of'

the train following one deenergization, before the relay is again energized, thus restoring the circuit to its normal condition. But when the relay N is de-ene'rgized, the slow release relay J is energized. When gizcd in the normal direction and de-ener- Ill) ' N isenergized. The relative lengths of time of this cycle may be regulated by variation in the time elements of the various elements of the circuits. When the lamp 200 flashes the engineman knows that he is approaching a caution signal and may conduct himself accordingly. As the train passes the point B, the reversed relative polarity of the track circuit current causes the relay 'N' to be energiz ed in the reverse direction and this deenergizes magnet H- and energizes magnet M, thus imposing on the train a speed limit of miles per hour. As'the train-passes the impedances v14 and. 15, the interruption of the local current de-energizes the magnet M and the train is prevented from proceeding at a speed in excess of 10 miles per hour.

In the modified form of train carried apparatus shown in Fig.. 7 I have omitted the magnets H and M with their controlling contacts for the sake of simplicity. Also I have omitted, for the same reason, the circuits for the control of windings 37 and 38 of relay N.' The circuit for the first slow acting relay J is the same as in Fig. 6', but a second slow acting relay U has been added, and this relay is inserted in the circuit in place of the lamp 200 in Fig. 6. The circuit for lamp 200 is now from the left hand terminal of the batteryIO through 'wires 47 and 65, front contact 6667 of relay J, wire 68, front contact 68 of relayU, wire 60, lamp 200 and wire 52 back to right hand terminal of battery 0. This'circuit is closed only when relays J and U are both energized. The operation of this apparatus in the zone where local current is intermittent; 1y supplied to the rails is as follows; When the local current is interrupted the first time the relay N is de-energized and so closes its back contact 40-44. This closes the circuit for the slow-acting relay J which becomes energizedand subsequently remains closed during the intermittentoperation of rela N. When relay N is energized again it wi 1 close the circuit for the slow-acting relay U, which latter will subsequently remain closed because of its slow-release characteristic. As soon as relay U closes, the lamp 200 will be lighted and will continue to burn steadily until the intermittent operation of relay .-ceases.

Fig. 8 I have shown the same apparatus as in Fig. 7 except that the circuit for thelamp 200 passes from wire 47 through wire 57, back contact 4044 of relay N, and

thence. as before to battery 0, thus including-back contact 4044 in its circuit. The operation is exactly as in Fig. 7 exceptthat the lamp 200 now lightsonly when relay N is de-energized thus giving aflashing indi: cation, lnstead of a steady lndlcatlon as was the case in Fig. 7.

. In Fig. 2, the apparatus is the same as that shown. in Fig. 1 except that each track relay R- is in this case a three-position two-element relay having one winding 7 O constantly supplied with alternating .current from the sec:

ondary winding 71 of the associated trans-.

former G. The other winding 72 of the relay R is connected across therails 'at the entrance end of the section. The track circuit current is, under these conditions, supplied from a windin 4 on the transformer G and the relative po arity of the current is controlled by the contact fingers 73 and 74 on the relay R. Referring particularly to transformer G, the associated relay Rfias. shown in the drawing, is energized in the normal direction. In this position the left hand terminal of secondary winding 4 is connected to rail 2 through wire 83, normal contact 73-75 of relay R and wire 81 and the right hand terminal of winding 4 is connected to rail 2 through normal contact 7478 of relay Rand wire 82. When relay R is energized in the reverse direction the left hand terminal is connected to rail 2* 7 through wire 84, reverse contact 73-'77 of relay R and wire 81 and the right hand terminal of this winding is connected to rail 2 through Wire 86', reverse contact 7480 and wire 82. It is clear,'therefore,

that-track circuit current of the same rela"- tive polarity which I shall term normal relative polarity is supplied to therails of .the section to the left of point A when relay lay R .and wire 81. In this case track'circuit current of theother relative polarity which I shall term. reverse relative polanity is supplied to the rails of the section 'to the left of A. The winding 18 of each transformer G, which winding supplies local current to the rails of the adjacent section'between the impedances 15 and 16, is-controlled by means the contact finger 88 on the associated re ay R. Referring particularly to transformcr'G the windingfl8 has a circuit which passes from its left-hand terminal through wire 89 to the mid-point of the impedance 15, through both rails of the section in parallel to the impedance 16, wire 94, reverse contact 88-91 of relay R wire 92, winding of slow-acting relay E .wire 97, back contact 3l32 of relay E wires 96 and 95, back to the right hand terminal of winding 18 on transformer G This circuit is closed only when the relay B is energized in the reverse direction and relay E is de-ene1"gizecl, but as soon as current starts to flow through this circuit the relay E is picked up, breaking the circuit through its back contact. This relay then becomes de-energized and the cycle is'repeated with the result that the portion of section AB between impedances 15 and 16 is supplied with an intermittent flow of alternating currentv as long as the relay B is energized in the reverse direction, thus actuating the train carried apparatus of Figs. 6, 7 or 8 exactly as in Fig. 1. Thecircuit for the windin 18 is provided witha branch which passes from wire 94 through normal contact 88-90 of relay R and wire 93 back to wire 95, thus omitting the slow-acting relay E This circuit is closed only when the relay R is energized in the normal direction in which case local alternating current is .constantly supplied to the rails of the section AB between the impedances 15 and16 by the winding 18 of transformer G Thus itis seen that exactly the same conditions of local and track circuit current exist in this case for a given conditionof trafiic, in advance as for Fig. 1.

Another arrangement of trackway circuits embodying my invention and arranged to co-operate with the train-carried apparatus shown in Figs. 6,7 and 8 is shown 'in Fig. 3. In this case I obtain the same results as in Figs. 1 and 2 but Irevrse the local current instead of the track circuit current to produce the intermediate speed condition. Each track section is providedwith a transformer designated by the reference character X with an exponent corresponding to the location, and a thermostat designated by'the reference character Y with an exponent corresponding to the location.

Each transformer Xis provided with three windings, 125, 126 and 127, and each thermostat'isprovidedwith a heating coil 120 and a movable finger 121 which normally closes the contact 121122. When the heating element 120'is energized, the finger 121 is moved to the left i and closes the contact 121-123. Referring particularly to section A-B the circuits for the local current are as follows: from'the left hand terminal .of the winding 18 of transformer .GB,'through wires 101 and 112' to the mid-point of, the impedance 16,

through both the rails'of section A-B in parallel, through impedance 13, wire 130,

winding 126 of transformer X "wire 113,

front contact 23 -24: of relay R and wire 116 back to the right hand terminal of the on transformer X is closed only when relay B is enr ed,

under which condition local current 0 normal relative polarit is supplied to the rails of section AB t roughout their length. A branch is provided for this circuit which branch passes from Wire 101 through wire 118, contact 121-123 of thermostat Y Wires 131 and 117-, to rails of section A-B through impedance 15. The circuit is closed through this branch only when thermostat Y is energized, under which condition local current is shunted away from that portion of section AB between impedances 15 and 16. vThe winding 19 of transformer Gr is provided with a circuit which passes from its left hand terminal through wire 132, back contact 23-41401? relay R wire 113, transformer winding 126, impedance 13, then through the rails of section A-B in parallel, impedance 15," wire 117, and wire 109 back to the right hand terminal of the S8 orrdary 19 of transformer G This circuit is closed only when relay B is 'de-energized and section A B is then supplied with local current of reverse relative polarity between impedances 13 and 15. The heatin element 120 of thermostat Y 'is provided yvith a circuit which passes from the up er terminal of Winding 125 on transformer i through wire 119, contact121-122 of thermostat Y winding 120 of thermostat Y, and wire 124 back to the lower terminal of winding 125 v This circuit is closed only when the contact -121-122. of thermostat Y is closed. The transformer X is provided with a winding 127 constantly sup-' plied with alternating current from. generator 12 through line wires 11, 11, and wires 128 and 129. Each transformer X is so constructed and connected that when the local current supplied to winding 126 thereof. is of normal relative polarity with respect to the-track circuit current, the voltages induced in winding 125 by the currents in windings 126 and 127 oppose each otherat any instant and conse uently no current flows in winding'125. S ould the relative polarity of the current in winding126 be reversed the voltages induced in winding 125 would be additive-and analternatin d1fier-. ence of potential would be created ietween the terminals of winding 125.

Ill

The operation of this apparatus is as fol- I lows: As shown in Fig. 3, a train V occupies the sectionto the right of C. The relay R is de-energiz'ed thus closing the circuit for winding 19 of transformer Gr which supplies local current of reverse relative polarity to the rails of section B-C between the impedances 13 and 15.while no local current is supplied to'the rails of ,this section from impedance 15 to impedance 16; The relay R is energized, thussu plying local current of normal elative po arlty to the rails of section A-B between impedances 13 and 16. In transformer X the voltages induced in winding 125 b currents in windlngs 126 and 127; are ad itive and the winding 125 is energized, thus heating the thermostat Y? which closes the contact 121-123 and short circuits the rails of the section AB. between impedances 15 and 16, thus reducing the local current through that por-. tion of the section to such' value that the train carried relay N willbe de-ener'gized.

But the opening of contact 121122 on the thermostat will de-energize its heating coil which will allow contact 121--122 to close again thus repeating the cycle as long as current of reverse relative polarity is supglied to the winding 126 of transformer The relay R is energized, thus supplying local current of normal relative polarit to the rails of the section to the leftof throughout its entire len h. It will be noted thatthe voltages in need in winding 125 of transformer X by the currents in winding 126 and 127 now are opposite in direction and being equal and opposite the result is zero induced voltage in winding 1 125' and hence the thermostat Y is not ener- '1 and 2 but by dilferent means.

gizedu It is evident that the interm'ittent supply of alternating current to the rails of a portion of the sectlon in rear of a caution signal as at S is accomplished as in Fig. 4 shows-another arrangement for accomplishing the same result-as the apparatus shown in Figs. 1, 2 and 3, and is exactly the same as that shown in Fig. 3 except that each thermostat Y is provided with a second contact finger 121 mechanically operated by finger 121 but electrically insulated therefrom. Finger 121 connects the left hand terminal of secondary 18 on transformer G to either impedance 15 For impedance 16 .ofthe section in rear of the thermostat, thus alternately supplying alternating local current to the rails of the section between the entrance. and, the exit end and between the entrance end and an intermestituted for the the transformenX The other winding 132 is provided with a circuit which passes from line wire'11 through wire 133, winding 132 of rela W wire 134, an element 100having a igh positive tem erature coeflicient, and wires 136 and 135 to 'ne wire 11". This .taneous relative particularly to relay W, the winding 99 is energized from the secondary 98'0f' circuit is provided with a-branch which passes from the wire 134 through wire 14.0,

normal -contact 103-107 of relay W and wire 141 back to wire 136. This branch is energized. The primary winding 126 is supplied with current of the one or the other relative polarity according as the localrurrent supplied tothe section A--B.is of normal or reverse relative polarity. Since the current supplied to winding 132 of relay vW is always of the same instantaneous relative polarity, it follows that the relay will be energized in the normal or the reverse direction depending upon the inst-an-.

I polarity of the local current supplied to section A-B. I

As shown in the drawing, the section to the right of C is occupied by avehicle V.

This interrupts, as before, the track circuit current in this section and causes re'lay R to be de-e nergized. Thus local current of reverse relative polarity is supplied to the rails of section BO between impedances 13 and 15 but no local currentis supplied to the rails of this section between impedances- 15 and 16. The section to the left of A is supphed with local current of normal relative" polarity throughoutits length. The

reversal of local current in section BC causes relay W to be energized in the reverse direction so that the current in winding 132 of relay W is forced to flow through the unit 100. The current raises the temperature of this unit and .due to its high positive temperature coefficient, the resistance of this unit is increased thus decreasing the current through the winding 132 which allows relay W to open, closin its back contacts. This disconnects the left liand side of transformer secondary 18 from impedance 16 of section A-B and connects it-to impedance 15 through back contact 102105. The branch through back'contact 1037-142 and unit 138 is also closed. As this unit heats up from the current passing through it, the resistance decreases and when the current has reached the'required value the relay W is picked up in the reverse direction and the element 100, having cooled oflf, repeats the cycle. Thus the current between impedances 15 and 16 of a' section is alternately supplied and interrupted in rear of a caution signal and co-operates with the train carried equipment asexplained hereinbefore.

.Although I have herein shown and described only a few forms andai'rangements of railway trafiic controlling apparatus cmrue-7,577

bodying my. invention, it is understood that various changes and modifications may ,be made therein within the scope 'of the appended claims, without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. Railway traflic controllin apparatus comprising track rails, means or applying an alternatingdiflerence of potential across said rails and another'alternating difference of potential along'said rails, means for at times intermittently interrupting the supply of one of said potential differences to the rails, train carried governing means controlled jointly by the currents in the track rails due to said potential differences but not affected by said intermittent interruption of the one difference of potential, and other train carried governing means responsive to said I intermittent interruption of said one difference of potential. I

2. Railway traflic controlling apparatus comprising track rails, means for applying an alternating difference of potential across said rails and another alternating difference of potential along said rails, means for at times intermittently interrupting the sup: ply of one of said potential differences to the rails, train carried governing means controlled jointly by the currents in the trpck rails dueto said p'otential differences iut not affected by said intermittent interruption of the one difference of potential, and a train carried signal responsive to said intermittent interruption of said one diflerence of potential. i

3. Railway trafiic controllin apparatus comprising track rails, means or'applying an alternating difierence of potential across said railsand another alternating difference of'potential along said rails, means for atv times intermittently interrupting the supply of the second of said differences of potential, train carried governing means controlled jointly by the currents in, the track rails due to said potential differences but'not affected by said intermittent interruption of the one d fference ofpotential, and other train carried governingmeans responsive to said .one

difference of potential.

4. Railway traffic controlling apparatus comprising track rails, means for applying an .alteriiating difference of potential across said rails and another alternating difference of potential along said rails, means for at times intermittently interrupting the supply of the second of said differences of potential, train carried governing means con-' trolled jointly by the currents in said track rails due to said potential differences but not affected by said intermittent interrup tion of the second difference of potential,

and a train carried signal responsive to the intermittent interruption of the second difference of potential.

5. In-combination, a section of railway track, means for supplying alternating cur-- rent to the rails of said section in series,

means for supplying a second alternating current of one relative polarity or the other to the rails of'said section in parallel between the entrance end and an intermediate point in the section, means for supplying a third alternating current to the rails of said section in multiple between said interme diate point-and the exit end of the section,

means for periodically interrupting said third current, and a train carried indicator controlled by said currents.

6. In combination, a section ofrailway track, means for supplying an alternating current of one relative polarity or the other 7. In combination, a section of railway track, a trackway circuit comprising the two rails of said section in series, a second trackway circuit compris ng the two rails 'ofsaid section in multiple between the entrance end and'an intermediate point in the section, a third trackway circuit comprising the two rails of said section in multiple between the exit end and an intermediate point in the section, means for supplying alternating currents to the said circuits, means for reversing the relative polarity of the current in one of the first two said circuits, means controlled by traffic conditions in advance for periodically interrupting the current in the said third. circuit,- and a train carried indicator responsive to said periodic interruption but not responsive to steady condition of the current in saidthird circuit.

8.111 combination, a section of railway a train carried indicator controlled in part by said current.

9. In combination, a section ofrailway track, a trackway circuit comprising the two rails of the section in parallel between the exit end and an intermediate point in the section, a trackway signal controlled by traflic conditions in advance, fmeans. con-1 trolled by said signal for intermittently supplying alternating current to said circuit, and a train carried indicator controlled in part by said current.

10. In combination, a section of railway track, a trackway circuit comprising the two rails of the section in parallel between the exit end and an intermediate point in the section, a trackway signal controlled by traffic conditions in advance, aslow-acting rclay, means controlled by said signal and said relay for intermittently supplying alternating current to said circuit, and a train carried indicator controlled in part by said current.

11. In combination, a first, a second and a third section of railway track, a track relay for the third section, a track relay for the. second section, a trackway circuit comprising the 'two rails of the first section in parallel between the exit end and an. inter-' mediate point in the.section, means controlled by said relay for intermittently supplying said, circuit with alternating current, and a train carried indicator controlled'in part by said current.

12. In combination, a section of railway track, a train carried relay having two windings, n'ieans controlled by alternating ourrent flowing in the same direction in the two rails of said section for energizing one winding of said relay, me'anscontrolled by alternating current flowing in opposite dire'ctions in the two rails of said section for energizing the other winding of said relay, means for supplying a periodically interrupted alternatino local current tothe rails of the section in parallel, a train carried indicator,

and means controlled by said relay for. alternately energizingand'de-energizing said indicator when said relay is alternately ener- 'zed and de-ener ized' h p 1,3. In COIIllJlIlRtIOIl, a section of railway track, a train carried relay having two windings, means controlled. by alternating current flowing in the same direction in'the two rails of said section for energizing one winding of said relay, means controlled by alternating current flowing in opposite directions in the two rails of said section for energizing the other winding of" said relay, :1 slow-acting relay provided with a circuit including a source of energy and a bacli contact on saidjfirst relay: and an indicator provided with 'a circuit includinga source of energy, a front contact on said slow-acting relay, and either a normal or areverse .contact on said first relay.

p 14. In combination, a railway track, means for at tunes continuously supplying saidtrack with energy andfor at other times periodically 'interruptingthe supply of such energy, andtrain carried governing apparatus responding selectively to such continuous and periodically interrupted supply, of en-' ergy.

15. In combination, a railway track, means for at times continuously supplying said track with energy and for at other times periodically interrupting the supply of such energy, a main'train carried relayrespond ing to both the continuously supplied and the periodically interrupted supply of encrgy,.a slow releasing relay on the train energized each time said main relaybecomes de-energized-and designed to remain cont-racltway, a slow releasing relay on the train continuously energized when said main relay is operating in response to periodically interrupted trackway energy, and a signal controlled jointly bysaid main and slow releasing relays.

17. In combination, a railway track, means for at times continuously supplying said track with energy and for at other times periodically interrupting the supply of such energy, and t 'aflic governing apparatus responding selectively to such continuous andperiodically interrupted supply. of energy.

18. In combination, means for at times continuously supplying said track with energy and 'for at other times periodically interrupting the su ply of such energy, a main train carried re ay arranged to be continuously energized during the continuous supply of energy to the track a railway 5 track,

and to open periodically during periodic in- 1 terruption of such energy supply, a slow releasing relay on the train controlled by saidmain' relay and arranged to be continuously closed during operation of the main relay in response to periodic interruption of the energy supply, and signaling means on the train controlled by said main and slow releasing relays.

19. In combination, a'railway track, means I for supplying said'trac'k with-periodically interrupted energy, and train carried apparatus selectiyely responsive tosuch periodically interrupted energy but not to energy continuously supplied.

20. In combination, a railway track, means for supplying said track with periodically interrtfptedenergy, a main train carried relay arranged to open periodically in response to periodic interruption of such energy supply, a slow releasing relay on the train controlled by said main relay and arra ged to be continuously closed 'during oper tion of the main relay in responseto peri dic interruption of the energy supply, and signaling means on the train cont-rolled by said main and slow releasing relays.

21. In combination,- a railway track, means for at times Continuously supplying said track with energy and for at other times periodically interrupting the supply of such energy, a main relay arranged to be continuously energized during the continuous supply of energy to the track and to open' periodically during periodic interruption of such energy supply, a slow releasing relay controlled by said main relay and arranged to be continuously closed during operatlon of said'main relay in response to periodic interruption of the energy supply, and traffic governing apparatus controlled by said main and slowreleasing relays.

22. In combination, a railway track, means for supplying said track with periodically interrupted energy, a main relay arranged to open periodically in response to periodic interruption of such energy supply, a slow releasing relay cont-rolled by said main relay and arranged to be continuously closed during operation of said main relay in response to periodic interruption of the energy supply, and traific governing apparatus con- {rolled by said main and slow releasing reays.

In testimony whereof I aflix my signature.

HERBERT A.- WALLACE; 

